In recent years, display elements of image display devices including television receivers are shifting from conventional cathode-ray tube displays to thin-screen display devices to which thin-screen display elements including liquid crystal panels and plasma display panels are applied. This enables the display device to be thinner. A liquid crystal display device requires a backlight unit as a separate lighting device because a liquid crystal panel used therein is not a light-emitting component. Examples of the backlight units include backlight units described in the following Patent Documents 1 and 2. In the backlight unit described in Patent Document 1, a light source unit is configured by arranging a plurality of LEDs (light sources) on a board, and the light sources are two-dimensionally arranged by arranging the plurality of light source units. In the backlight unit described in Patent Document 2, a white or silver reflection sheet is provided on a chassis on which a light source is provided, and thereby light from the light source is reflected to a liquid crystal panel side by the reflection sheet.    Patent Document 1: Japanese Unexamined Patent Publication No. 2007-317423    Patent Document 2: Japanese Unexamined Patent Publication No. 2008-304839